21.11.3 TCNT1L – Timer/Counter1 Low byte
When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When addressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to these offset addresses.
| Name: | TCNT1L |
| Offset: | 0x2C |
| Reset: | 0x00 |
| Property: | When addressing I/O Registers as data space the offset address is 0x4C |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| TCNT1L[7:0] | |||||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Bits 7:0 – TCNT1L[7:0] Timer/Counter 1 Low byte
The two Timer/Counter I/O locations (TCNT1H and TCNT1L, combined TCNT1) give direct access, both for read and for write operations, to the Timer/Counter unit 16-bit counter. To ensure that both the high and low bytes are read and written simultaneously when the CPU accesses these registers, the access is performed using an 8-bit temporary High Byte Register (TEMP). This temporary register is shared by all the other 16-bit registers. Refer to Accessing 16-bit Registers for details.
Modifying the counter (TCNT1) while the counter is running introduces a risk of missing a compare match between TCNT1 and one of the OCR1x Registers.
Writing to the TCNT1 Register blocks (removes) the compare match on the following timer clock for all compare units.